Method and apparatus for making dental impressions



Feb. 25, 1941. 0, J LUBB-QCK' v 2,233,020

METHOD AND APPARATUS FOR MAKING DENTAL IMPRESSIONS Filed May 2, 1938 IN NTOR OSWIQL J: BBOCK BY 7/15 ATTORNEY Patented Feb. 25, 1941 UNITED STATES- METHOD AND APPARATUS FOR MAKING DENTAL IMPRESSIONS OswaldJ. Lubbock, Alameda, Calif.

Application May 2, 1938, Serial No. 205,427

2' Claims.

My invention relates to dental impressions emplayed for making plates, bridges and the like; and the broad object of the invention is to provide an improved method of taking theimpressions, andtofurther provide an improved tray for holding the impression material, whereby the tray and impression are easily removed from themouth.

The invention possesses. other objects and features of advantage, some of which, with the foregoing, will be set forth in. thefollowing description of my invention. It is to be understood that I do not limit myselfto. this. disclosure of species l of my invention, as Imay adopt variant .embodir ments thereof within the scope of the claims. Referring to the drawing: Figure 1 is a perspective View of the template tray for taking a preliminary impression" at the v upper region of a patients mouth; and Q Figure 2 is a side elevational view of the wall or partition which is shaped from the preliminary impression as a template.

Figure 3 is an exploded plan view of the sectional tray for making the final impression, and shows the partition between the sections.

Figure 4 is a plan view of a substitute element for one of the tray sections when only half of the tray is used.

Figure 5 is a vertical sectional view taken across the partition in the assembled tray, and showing the final impression.

Figures 6, '7 and 8 are views similar to Figures 1, 2and 3, respectively, but showing elements for taking an impression of the lower jaw.

In terms of broad inclusion, my method of making a dental impression comprises first taking a preliminary impression; then shaping the edge of a relatively stiff sheet to the contour of impression forming surface, using the prelimina'ry impression as a template; and then applying the sheet as a retaining wall for the final impression. With a large impression the sheet is preferably applied as a dividing wall to split the impression for facilitating removal of the latter from the mouth. The tray of my invention for holding the final impression is made in two sections between which the preformed partition is slidably mounted for adjustment to the height of the impression; and the partition is preferably formed of a relatively cheap material, such as fiber, to permit discarding after use.

In greater detail, Figures 1 to 5 of the drawing show the apparatus of my invention as adapted for taking an impression at the upper regions of a patients mouth. Figure 1 shows the template tray for holding'a material, such as plaster" the desired portion of the mouth, and holding it thus until the plaster is' set. This template impression is taken at'a predetermined point across the surface where thefinal impression is to be taken and thus gives the contour at that point.

The preliminary impression, being merely for the. purpose of'providing a template, .is relatively narrow. and the tray is easily handled. and the impression readily removedfrom the mouth afterthe plaster has set. The template tray is preferably of rubber formed in one piece and having a handle 2 andan elongated body' 3 with side walls 4; These walls are cut back'at 6 to clear thejaw, and the walls are preferably fiaredoutwardlyandtapered toward'the topto give greater flexibility. The walls are thus capable of spreading out somewhat at the edges to give a measure of adjustment when the tray is pressed up against differently shaped surfaces.

After the preliminary impression has been made it is used as a template to shape the upper edge 1 of a retaining wall or partition 8 to be used in taking the final impression. See Figure 2. This wall is made of a relatively stifi sheet material, such as fiber. Ordinary cardboard is preferably used, since it is easily cut, and also is cheap enough to discard after using. In order to prevent the plaster from sticking to it, the fibrous sheet is preferably treated, as by impregnating with paraffine. After the sheet is cut, it presents an upper edge complementary tothe contour of the gum and adjacent mouth surfaces at a predetermined line across the surface from which the final impression is tobe taken.

Figure 3 shows the tray for holding the final impression, comprising a body 9 having a projecting handle I I. This tray is a permanent part of the apparatus, and is preferably of metal. The assembled tray holds an impression of the entire upper jaw and roof of the mouth, and is shaped after the manner of trays usually provided for this purpose. In order to facilitate removal from the mouth, my tray is split transversely to divide the body and handle into two half sections.

Means are provided for holding the tray sections together in proper alignment. For this purpose a pair of aligning pins l2 are slidably fitted on the handle, and a fastening screw I3 is arranged between the pins. By loosening the screw and pins the half sections may be removed separately from the mouth.

The preformed partition 8 is used in connection with this tray and is slidably mounted in a 1 slot between the body sections 9 so that the partition extends transversely across the middle of the tray. The width of the slot is such as to hold the partition vertically with a snug sliding fit when the tray sections are clamped together.

Adjustment between the sections may be made by shims interposed between the handle portions. In the use of this tray the parts are assembled and the cupped sections on each side of the transverse partition filled with plaster I4. At this time partition 8 is raised well above the body of plaster to insure engagement with the surface of the mouth, as indicated by dotted lines in Figure 5.

The whole is then inserted in the mouth and pressed upwardly against the jaw. Partition 8 strikes first and the tray and plaster then slide up along the partition until the plaster has been firmly pressed in place. Since partition 8 was previously shaped to the contour of the mouth surface at the point where the artition now lies, the upper edge of the partition registers exactly with the impression surface and completely separates the half sections of the cast.

After the plaster has set, the tray sections are removed separately. The half sections of the cast impression may now readily be separated by a pry from below since they do not stick to the paraflined surface of the partition. Breaking of the cast to remove it from the mouth, as is often required with a one-piece impression, is therefore avoided. The half sections of my cast are not only readily removed from the mouth, but are also easily reassembled with the partition to produce a perfect and faithful impression.

When it is desired to take an impression of only half of the upper jaw, one of the tray sections is replaced by an element l5 such as shown in Figure 4. This element merely completes the partition holding slot and provides a backing for the outer side of partition 8 to prevent the latter from spreading. The partition in this case functions largely as a retaining wall for the plaster.

Figures 6 to 8 illustrate apparatus for taking an impression of the lower jaw. Figure 6 shows a rubber template tray l6 having depending side walls H to hold the preliminary impression. Figure '7 shows a wall or partition l8 shaped to fit across the lower jaw; and Figure 8 shows the sectional tray I9 for the final impression. The

tray in this case is C-shaped as is usual with trays for lower jaw impressions.

I claim:

1. Dental apparatus comprising a tray having separable sections for holding an impression making material when the latter is pressed against a surface in the mouth, and a division sheet slidably mounted between the tray sections for movement from an initial position projecting above said material to a position flush with the final impression as formed by the mouth surface when the assembled tray is pressed against sai surface.

2. The method of making a dental impression which comprises shaping the edge of a sheet to the contour of a mouth surface, placing a quantity of impression making material at each side of the sheet with the shaped edge of said sheet initially disposed above said material, then pressing the material and said division sheet against the mouth surface to force the sheet down flush with the final impression as formed by the mouth surface, and then separating the impression along the plane defined by the division sheet and removing the parts from the mouth.

OSWALD J. LUBBOCK. 

